(1) Field of the Invention
The present invention relates to a compactly stowed deployable antenna system. More particularly, the antenna system is operable on two frequencies simultaneously.
(2) Description of the Prior Art
As recited in U.S. Pat. No. 5,091,732, Lightweight Deployable Antenna System in which I was a co-inventor with Jeffrey Kornblith, underwater installations and submersible vehicles occasionally require antennas above the surface of the water for transmission of radio signals to other installations and vessels. Space applications similarly may require compact deployable antenna systems. Field applications of the military rescue units, explorers and the like also require compact antenna assemblies for ready transport and rapid deployment.
The device of the aforementioned patent met these requirements. The present inventive device is a patentable modification having circular polarization and a wider bandwidth than the Deployable Antenna System in U.S. Pat. No. 5,091,732. The prior antenna system allows a lightweight deployable antenna to operate within only one relatively narrow band of frequencies. This narrow range of frequencies is inadequate for compatibility with communication systems which require simultaneous operation at two relatively widely spaced frequency bands such as 250 MHz and 350 MHz. The circular polarization gives the system satellite compatability.
Most antennas gain wide bandwidth or dual band operation by the use of large, heavy, bulky elements that are not compatible with the features of the present invention. As an example, U.S. Pat. No. 3,176,298, Attachment for Antennas to Reduce Operating Frequencies, by W. E. Nettles shows coils similar to those in the present invention. However, the arrangement of these coils as shown by Nettles would not be suitable in the present invention as excessive snagging and scraping would take place upon attempted deployment of the antenna system.